Method and apparatus for burning liquid fuels

ABSTRACT

A liquid fuel burner evaporates liquid fuel by extended surface contact between the fuel and a moving stream of combustion gas before introduction of the combustible mixture into a combustion chamber. Unevaporated fuel may be recirculated, and the combustion gas may be heated prior to contact with the fuel, as by admixture with a portion of flue gases.

United States Patent 1,063,412 6/1913 Buckman,Jr

Inventor Laszlo Gabor Budapest, Hungary Appl. No. 817,419 Filed Apr. 18,1969 Patented Oct. 19, 1971 Assignee Nikex Nehezipari KulkereskedelmiVallahat Budapest, Hungary Priority Apr. 20, 1968 Hungary GA-897 METHODAND APPARATUS FOR BURNING LIQUID FUELS 3 Claims, 15 Drawing Figs.

US. Cl 431/328, 431/330, 431/11, 431/208 Int. Cl F23d 13/14 Field ofSearch 431/117,

References Cited UNITED STATES PATENTS 1,592,238 7/1926 Walker 431/3301,676,501 7/1928 Moors 431/208 2,003,700 6/1935 Sloyan 431/208 X2,661,054 12/1953 Hyatt et a1. 431/11 X 2,735,481 2/1956 Reichhelm431/346 X 3,199,568 8/1965 Baumanns et al.... 431/328 X 3,238,991 3/1966Goldmann et al. 431/11 3,263,732 8/1966 Eisenkraft 431/330 X 3,418,97912/1968 Reichmann 431/328 X FOREIGN PATENTS 471,326 2/1929 Germany431/330 741,998 12/1955 Great Britain 431/330 Primary Examiner FrederickL. Matteson Assistant Examiner-Robert A. Dua Attorney-Young & ThompsonABSTRACT: A liquid fuel burner evaporates liquid fuel by extendedsurface contact between the fuel and a moving stream of combustion gasbefore introduction of the combustible mixture into a combustionchamber. Unevaporated fuel may be recirculated, and the combustion gasmay be heated prior to contact with the fuel, as by admixture with aportion of flue gases.

PAIENTEDUBI 19 ml 3 s 1 4, 2 a2 SHEET 10F 3 Fig.7

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INVENTOR BY #JW ATTORNEYS PATENTEDUET 19 Ml SHEET 2 OF 3 INVENTORATTORNEYS METHOD AND APPARATUS FOR BURNING LIQUID FUELS The presentinvention relates to apparatus for burning liquid fuels, characterizedby vaporization of the fuel prior to combustion.

It is an object of the present invention to provide apparatus forburning liquid fuels, in which combustion of the fuel is substantiallycomplete and the flue gases are substantially free from unburnedmaterial.

Another object of the present invention is the provision of apparatusfor burning liquid fuels, characterized by novel ways of preheating thegaseous evaporation medium.

Finally, it is an object of the present invention to provide apparatusfor burning liquid fuels, which will be relatively simple andinexpensive to manufacture, easy to operate, maintain and repair, andrugged and durable in use.

Other objects and advantages of the present invention will becomeapparent from a consideration of the following description, taken inconnection with the accompanying drawings, in which:

FIG. I is a somewhat schematic view, in longitudinal section, of a firstembodiment of apparatus according to the present invention;

FIG. 2 is an enlarged fragmentary cross section of a portion of theembodiment of FIG. 1;

FIG. 3 is a top plan view of the structure of FIG. 2;

FIG. 4 is a view similar to FIG. I, but showing a second embodiment ofthe invention;

FIG. 5 is a view similar to FIG. I, but showing a third embodiment ofthe invention;

FIG. 6 is an enlarged fragmentary view of a portion of the embodiment ofFIG. 5, it being understood that FIG. 6 is to FIG. 5 as FIG. 2 is toFIG. I;

FIG. 7 is a cross-sectional view taken on the line A-A of FIG. 6;

FIG. 8 is a view similar to FIG. I, but showing a fourth embodiment ofthe present invention;

FIG. 9 is a fragmentary side elevational view of a further embodiment ofthe present invention, showing only that portion thereof by which theliquid fuel is introduced into the stream of gaseous evaporation medium;

FIG. 10 is a side elevational view of the structure of FIG. 9;

FIG. 11 is a view similar to FIG. I but showing still another embodimentof the invention;

FIG. 12 is also a view similar to FIG. I, but showing a still furtherembodiment of the invention;

FIG. I3 is a schematic bottom plan view, with parts removed for clarity,of the embodiment of FIG. 12; and

FIGS. 14 and 15 are views similar to FIG. I, but each showing a stillfurther embodiment of the present invention.

Referring now to the drawings in greater detail, and first to theapparatus of FIG. 1, there is shown apparatus for burning liquid fuels,comprising an evaporator I for liquid fuel from a storage container 2for the principal fuel to be burned. An auxiliary storage container 3contains a more volatile liquid fuel, which can be evaporated and burnedduring start-up. Fuel from container 2 or 3 is fed to a distributor 4 inthe evaporator I. If desired, the fuel from container 2 can be preheatedby preheater 5. The flow of fuel from container 3 is selectivelycontrolled by a valve 6, while the flow of fuel from container 2 isselectively controlled by a valve 7. In either case, the fuel flows todistributor 4, where it encounters vertically spaced horizontal plates 8and 9. A plurality of vertical wires 10 extend between plates 8 and 9,it being understood that liquid fuel flows from distributor 4 down wiresI0 filmwise, and then into a collector II.

An evaporation medium in gaseous phase, such as combustion air, passeshorizontally about the surfaces of the fuelwetted wires 10 and proceedsto a burner 12. Fuel which does not evaporate during passage along wires10 is collected in collector II and returned to container 2 by means ofa pump 13.

The air which evaporates fuel from wires 19 may be preheated by heater15 which is upstream of the wires I0 but downstream from the blower I6by which the air is impelled. Heater I5 may be electrically heated orfired by gas or another fuel, or may be heated by steam or combustionproducts. Thus, fuel coming from container 2 or 3 passes through conduitI7 and thence through distributor 4 to wires II) and collector II, theevaporated-fuel/comb'ustion-air mixture registering its temperature upona thermometer I8 or the like on its way to burner I2, from which itissues through a screen I9 that prevents backflash. The thermometer I8can control the fuel flow and/or the blower I6 and/or the heater I5, soas to maintain a constant predetermined temperature in the burnerbetween the evaporator and the screen I9. The air-fuel mixture isignited by means of an automatic electrical ignition device (not shown)disposed outside but adjacent screen I9, and which could be representedin the drawings by a simple vertical line adjacent screen I9 outsideburner 12.

Referring now to FIGS. 2 and 3, the particular mounting for the wiresIII will be seen to comprise a hole 20 through upper plate 8 which islarger than the wire It) so that wire 10 is surrounded by an annularopening through which the fuel may blow downwardly by gravity so as toform a continuous film about wire I0. The supports 2I, seen. in FIG. 3,center the upper end of wire III in the hole 20 and also the lower endof wire III in a corresponding hole 22 in lower plate 9.

Referring now to FIG. 4, it will be seen that evaporation can beperformed with less than the total quantity of combustion air. Themixture of air and evaporated fuel flows from the evaporator I into amixing chamber 23" where it is mixed with combustion air suppliedthrough a conduit 24 and then delivered to burner I2.

FIG. 5 shows an apparatus having an evaporator I wherein the evaporatorsurfaces are provided by vertical plates 25. The plates 25 are attachedto the upper and lower plates corresponding to plates 8 and 9 in FIG. I,in a manner similar to the attachment of wires It). The openingsrequired for the passage of liquid fuel can be provided] by corrugationof the ends of the plates 25 or by corrugations extending their entirevertical height, and the plates may be firmly fixed in slots 26 cut inthe upper and lower plates corresponding to plates 8 and 9 in FIG. I.See especially FIGS. 6 and 7 for this structure by which the flow ofliquid fuel is ensured. In order to increase the total surface of plates25 and improve the heat exchange, the plates 25 may be subdivided intosmaller surfaces or provided with latticelike structure of the type ofexpanded sheet screen or other type.

FIG. 8 shows another embodiment, particularly characterized by means forpreheating the combustion air by use of a portion of the flue gases.Preferably, the flue gas is removed from the combustion chamber, and isaccordingly at such a high temperature that only a very small amount(about 10 percent) is sufficient to produce the desired temperature ofthe combustion air for evaporating the fuell. Thus, atemperatureresponsive regulator 27 under the control of a thermometer 28or the like downstream of the evaporator regulates the quantity of fluegas which is educted through a conduit 29 from the combustion chamber30, the control 27 and the thermometer 28 being interconnected by acontrol line 31 in known manner. A throttle valve 32 regulates theamount of combustion air in the conduit 33 into which the conduit 29empties, and an injector 34i surrounds conduit 29 in conduit 33. Thecombustion air passing through conduit 33 thus educts flue gases throughconduit 29 because of the reduced pressure in the nozzle of injector 34.The amount of educted flue gases can be regulated by moving injector 34lengthwise in conduit 33 under the control of a rod 35 through aturnbuckle 36.

In the embodiments previously described, the liquid flows by gravityover the film-supporting surfaces. The embodiments of FIGS. 9 and I0show, however, that these surfaces can be dipped into and out of asupply of the fuel. Thus, in this embodiment, a horizontal shaft 37rotatably supports a drum 38 which has extended surfaces of wire orplate or the like, the lower half of drum 38 being immersed. in a fuelcontainer 39.

During rotation, the wetted surfaces enter the duct 40 to be subjectedto the action of the stream of evaporation medium such as the combustionair.

Also up to this point, the apparatus described has functioned byevaporating films of liquid from supports of extended surface area.However, it is also possible to provide extended contact surface betweenthe liquid and the gas, by other means. Thus, as seen in FIG. 11, anevaporator much like a stripping column may be provided, comprising aplurality of horizontal perforated plates 41 to the upper of whichliquid fuel is supplied. The fuel passes downwardly through the platesin the form of dropsand streams, and the evaporating medium from inlet43 passes upwardly through the plates in countercurrent flow, theunevaporated fuel collecting in a sump 42 whence it may be recirculatedby the pump 13 to the fuel storage container 2. In order to avoid theentrainment of droplets of liquid fuel in the emergent stream of vapors,labyrinthine baffles 44 provide a circuitous path for the vapors fromwhich droplets are expelled by their inertia.

The liquid fuel may also be sprayed into the evaporation medium. Thispossibility is illustrated in FIGS. 12 and I3, in which a verticallyelongated chamber 45 receives relatively rapidly upwardly flowingcombustion gas through inlet 43, and relatively slowly rising dropletsfrom a sprayer 46, the unvaporized portions of the droplets eventuallysettling out of the gas whereby the gas and the droplets havesubstantial movement relative to each other thereby to promoteevaporation.

FIG. 14 illustrates a combination of the spray principle of FIGS. 12 and13 with the vertical wire principle of FIGS. 1, 4 and 8. In the FIG. 14embodiment, the liquid fuel is sprayed from the sprayer 46, theunvaporized portions of the droplets impinging on the wires and runningdown into the collector II for recirculation. Instead of wires,obliquely disposed plates can be used in the embodiment of FIG. 14. g Inthe embodiments described up to this point, the quantity of fuel hasbeen determined by the temperature of the mix ture. However, thequantity of fuel may also be determined by metering the fuel itself. InFIG. 15, fuel is supplied by a metering device 47 such as a meteringpump, from container 2 to an evaporator l. The evaporator has surfacesof such extent and the temperature and velocity of the evaporationmedium are selected so that the quantity of fuel required for themaximum output will be evaporated. Provided that the predeterminedconditions are maintained, the fuel introduced into the apparatus willthus be completely evaporated.

The present invention thus solves the problem of handling incombustiblecomponents of the fuel. As is known, certain fuels may contain, forexample, 0.3-0.5 percent by weight of incombustibles, which either leavethe combustion apparatus as fly ash, or else accumulate in thecombustion apparatus as soot. But in the present invention, the fuel isin effect distilled, at least in those embodiments where unevaporatedfuel is recycled, so that only the relatively volatile components andhence the combustibles can be burned. The recycled fuel can thus containprecipitates washed down by the flow of fuel over the evaporationsurfaces or from the sump of the equipment; and these precipitates canbe removed by filtration or centrifugation or sedimentation anddecantation, from the fuel that is returned to the fuel storage.

In view of the foregoing disclosure, therefore, it will be evident thatall of the initially recited objects of the present invention have beenachieved.

Although the present invention has been described and illustrated inconnection with preferred embodiments, it is to be understood thatmodifications and variations may be resorted to without departing fromthe spirit of the invention, as those skilled in this art will readilyunderstand. Such modifications and variations are considered to bewithin the purview and scope of the present invention as defined by theappended claims.

Having described my invention, I claim: I. Apparatus for burning liquidfuel, comprising an evaporator chamber having boundary walls defining apassageway for a gaseous evaporation medium, extended surface meanshaving surfaces spaced apart in the direction of gas flow and disposedin said passageway between and extending transversely of said walls andwetted by the liquid fuel, an inlet for said gaseous evaporation mediumdisposed at one end of said passageway, an outlet for a combustiblemixture of said evaporation medium and evaporated fuel disposed at theopposite end of said passageway, said surfaces being spaced both fromsaid inlet and from said outlet, means for conducting the liquid fuelonto said surfaces, means to force said evaporation medium through theevaporator chamber along said surfaces to evaporate at least a portionof the liquid fuel in the evaporator chamber, means located before theevaporator chamber for preheating the evaporation medium, means forcollecting and recirculating unevaporated liquid fuel, and means forburning the combustible mixture at a location spaced from saidevaporator chamber and beyond said outlet and for separating saidsurfaces from the combustion of said combustible mixture.

2. Apparatus as claimed in claim 1 said surfaces comprising verticallyextending wires, and means to supply liquid fuel to upper portions ofthe wires to flow down the wires in films exposed to the evaporationmedium.

3. Apparatus as claimed in claim I, said surfaces comprising a rotor inthe evaporator chamber partially immersed in liquid fuel and partiallyin the path of said evaporation medium.

1. Apparatus for burning liquid fuel, comprising an evaporator chamberhaving boundary walls defining a passageway for a gaseous evaporationmedium, extended surface means having surfaces spaced apart in thedirection of gas flow and disposed in said passageway between andextending transversely of said walls and wetted by the liquid fuel, aninlet for said gaseous evaporation medium disposed at one end of saidpassageway, an outlet for a combustible mixture of said evaporationmedium and evaporated fuel disposed at the opposite end of saidpassageway, said surfaces being spaced both from said inlet and fromsaid outlet, means for conducting the liquid fuel onto said surfaces,means to force said evaporation medium through the evaporator chamberalong said surfaces to evaporate at least a portion of the liquid fuelin the evaporator chamber, means located before the evaporator chamberfor preheating the evaporation medium, means for collecting andrecirculating unevaporated liquid fuel, and means for burning thecombustible mixture at a location spaced from said evaporator chamberand beyond said outlet and for separating said surfaces from thecombustion of said combustible mixture.
 2. Apparatus as claimed in claim1, said surfaces comprising vertically extending wires, and means tosupply liquid fuel to upper portions of the wires to flow down the wiresin films exposed to the evaporation medium.
 3. Apparatus as claimed inclaim 1, said surfaces comprising a rotor in the evaporator chamberpartially immersed in liquid fuel and partially in the path of saidevaporation medium.